Amines and Carboxylic Acid Derivatives

Amines

• Amines are organic derivatives of ammonia, containing a nitrogen atom with a lone pair of electrons, making them both basic and nucleophilic.
• Amines can be classified as primary (1°), secondary (2°), or tertiary (3°) based on the number of alkyl (or aryl) substituents bonded to the nitrogen atom.

Nomenclature of Amines

• Amines with more than one functional group are named by considering the –NH2 as an amino substituent on the parent molecule.
• Amines can be named using the "N-alkyl" term(s) at the beginning of the name.
• Cyclic amides are called lactams.
• Nitriles are named by adding the nitrile suffix to the name of the corresponding alkane.

Properties of Amines

• Amines with fewer than five carbon atoms are generally water-soluble.
• Primary and secondary amines form hydrogen bonds and are highly associated.
• Amines have a distinctive odour, with low-molecular-weight amines having a fishlike aroma.

Substitution of the Hydroxyl Group

• Reactions involving the replacement of the hydroxyl group of a carboxylic acid with another nucleophilic group are important for preparing functional derivatives of carboxylic acids.

Preparation of Amides and Esters

• Acyl halides can be prepared by treating carboxylic acids with thionyl chloride (SOCl2) or phosphorus tribromide (PBr3).
• Acid anhydrides are derived from two molecules of carboxylic acid and amines.
• Amides are usually prepared by reaction of an acid chloride with an amine.
• Esters are prepared by reaction of an acid with an alcohol.

Reactions of Esters and Amides

• Esters undergo hydrolysis to yield carboxylic acids plus alcohols.
• Amides undergo hydrolysis to yield carboxylic acids plus amine on heating in either aqueous acid or aqueous base.
• Amides can also undergo reduction to yield amines.

Understand the chemistry of amines, their properties, and reactions involving substitution of the hydroxyl group in carboxylic acids.